Passive PC Heat Sinks, will these work for CREE COBS???

I was looking at something very similar to this before, but I cant find a size dimension for the raised profile portion on the mounting side to know if it would accomodate the size of a cxa/cxb cob.
 
The bottom of the heatsink is not flat. It has a raised stripe down the middle which is 30mm across (I used photoshop to work out it's size based on the heatsink being 77mm wide which I got off the manufacturer's website).

If you have a COB larger than 30mm then you'll have 2 sections down each side which are not in contact with the heatsink. A CREE CXB3590 is 34.85mm wide. Cheapo chinese COBs are 40mm wide.
 
The 3.945" profile from heatsink usa cut to 4" is about the same price. I have a few cut like this to run passive.

(edit: looks like the ones you posted have 50% more fins so not a great comparison)

Have you considered radial and pin sinks?
 
loftygoals said:
The bottom of the heatsink is not flat. It has a raised stripe down the middle which is 30mm across (I used photoshop to work out it's size based on the heatsink being 77mm wide which I got off the manufacturer's website).

If you have a COB larger than 30mm then you'll have 2 sections down each side which are not in contact with the heatsink. A CREE CXB3590 is 34.85mm wide. Cheapo chinese COBs are 40mm wide.
Click to expand...
I wonder if it would fit my cxa3070's,, they are smaller than the 3590's,, If i recall the thermal paste that comes on the pc heat sink will be the same size square as the pc heatsinks with fans I am currently running? here are the sinks I am using right now
https://www.amazon.com/ARCTIC-Alpin.../184-7203544-2592905?ie=UTF8&ref_=cm_sw_su_dp
 
churchhaze said:
The 3.945" profile from heatsink usa cut to 4" is about the same price. I have a few cut like this to run passive.

(edit: looks like the ones you posted have 50% more fins so not a great comparison)

Have you considered radial and pin sinks?
Click to expand...
have you got a link to the radial pin sinks please?,, thanks
 
loftygoals said:
The bottom of the heatsink is not flat. It has a raised stripe down the middle which is 30mm across (I used photoshop to work out it's size based on the heatsink being 77mm wide which I got off the manufacturer's website).

If you have a COB larger than 30mm then you'll have 2 sections down each side which are not in contact with the heatsink. A CREE CXB3590 is 34.85mm wide. Cheapo chinese COBs are 40mm wide.
Click to expand...

If it's really 30mm that should cover pretty much everything that isn't a CXB3590, CXB3070 and smaller, all current Veros, Citizens below 05x, anything Nichia.

That's a hefty chunk of metal, free shipping, and good availability, but would really only be good for about 12W of heat dissipation.

For comparison, a dedicated heatsink like this: https://www.cdiweb.com/ProductDetail/MODULEDXTRA9980B-mechatronix/574061/

Is the same price, pre-drilled, and is quite a bit better. Similar surface area, but a more effective design, but no good for a CXB3590 either. Try a pin with a wider base design for that cob.
 
churchhaze said:
I'm actually not sure on that. I've never used radial sinks personally. I just know they're oriented better for passive.
Click to expand...

Yeah, pins and radials do more with less. Wider seems better than taller for both, when comparing the same weight or surface area to C/W.

I know @OLD MOTHER SATIVA just ordered from http://www.heatsinkled.com

Not sure what the lead time was, or MOQ, but the prices were good.
 
quick turn around..have tracking #
will know eventually if they cool enough for 130B nichia at 31 w each

but if i use 4 per hlg-120h-48..i would have more like 25w each..?

and they would be more efficient?
 
JorgeGonzales said:
If it's really 30mm that should cover pretty much everything that isn't a CXB3590, CXB3070 and smaller, all current Veros, Citizens below 05x, anything Nichia.

That's a hefty chunk of metal, free shipping, and good availability, but would really only be good for about 12W of heat dissipation.

For comparison, a dedicated heatsink like this: https://www.cdiweb.com/ProductDetail/MODULEDXTRA9980B-mechatronix/574061/

Is the same price, pre-drilled, and is quite a bit better. Similar surface area, but a more effective design, but no good for a CXB3590 either. Try a pin with a wider base design for that cob.
Click to expand...
the sink you linked is for a very small cob,, i searched the web page for the correct heat sink for a 3070 and they run around 26 dollars per heat sink, , out of my price range,,
maybe Ill just stick with my pc sinks with fans, till they wear out
 
Tim Fox said:
the sink you linked is for a very small cob,, i searched the web page for the correct heat sink for a 3070 and they run around 26 dollars per heat sink, , out of my price range,,
maybe Ill just stick with my pc sinks with fans, till they wear out
Click to expand...

Yeah, no, they run about $9.50. I was responding to a general question about suitability for cob cooling vs the Arctic you linked, not to what was apparently a specific question about CXA3070s for yourself. I run a 28mm cob on the exact heatsink I linked, but the LES is 1mm smaller than a 3070.

Same shit, different holes: https://www.cdiweb.com/datasheets/mechatronix/ModuLED_Modular_Passive_Star_LED_Cooler99.pdf

Huge overkill: http://www.pacificlightconcepts.com/product/plc140mm-anodized-pin-heatsink/

Why not just just stick with what you have? Active is going to cool better and weigh less. It's also a pain to wire, and one more thing to break, but you've already gone through the trouble.
 
JorgeGonzales said:
Yeah, no, they run about $9.50. I was responding to a general question about suitability for cob cooling vs the Arctic you linked, not to what was apparently a specific question about CXA3070s for yourself. I run a 28mm cob on the exact heatsink I linked, but the LES is 1mm smaller than a 3070.

Same shit, different holes: https://www.cdiweb.com/datasheets/mechatronix/ModuLED_Modular_Passive_Star_LED_Cooler99.pdf

Huge overkill: http://www.pacificlightconcepts.com/product/plc140mm-anodized-pin-heatsink/

Why not just just stick with what you have? Active is going to cool better and weigh less. It's also a pain to wire, and one more thing to break, but you've already gone through the trouble.
Click to expand...
your right , i will stay with what I have for now,, ,besides when I turn my cob cooling fans on high, i can see airmovement in the tops of the colas,, so I am getting a 2 for one deal on the air flow
 
so using cpu heatsinks for passive cooling is bad idea? :D i got clu048-1212 working on 1400ma so can cpu heatink cool 50w led passivly? I'm goint to use cpu cooler with fans but really don't like fans it's noisy
 
Tsilo said:
so using cpu heatsinks for passive cooling is bad idea? :D i got clu048-1212 working on 1400ma so can cpu heatink cool 50w led passivly? I'm goint to use cpu cooler with fans but really don't like fans it's noisy
Click to expand...
if it has mass then a cooler can do pasive but cpus have a different powermanagement than leds....nithing wrong with fans they can drop your costs and triple or quadruple cooling rates...not too shabby
 
Abiqua said:
if it has mass then a cooler can do pasive but cpus have a different powermanagement than leds....nithing wrong with fans they can drop your costs and triple or quadruple cooling rates...not too shabby
Click to expand...
Heat is heat. A lot of those CPU coolers are far better than the pin heatsinks everyone uses, even passive. Most of those are designed to handle higher wattage than people are running these cobs.
 
I'm talking about intel default heatsinks can it be used as passive heatsink for 50w? has anyone done it? I don't have equipment to test it or do some advanced sht :D any experienced users?
 
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